Placenta previa (implantation of the placenta over the cervical os) and abruptio placenta (premature separation of a normally implanted placenta from the uterine wall) are serious problems of pregnancy. Abruption is responsible for over 20% of perinatal mortality, and the occurrence of placenta previa may comprise both the health of the mother and child; both generally require a C-section delivery. Very few studies of these conditions have been done; however, there is some evidence from case series that exposures such as prior C-section, induced abortion, smoking, and alcohol use may increase a woman's risk. Illicit drug use, specifically cocaine use, may also increase the risk for abruption. Until now, these exposures were not common enough to be evaluated as risk factors using case-control methods. The proposed is a multi-center, case- control study of placenta previa and abruptio placenta which will identify cases and controls from five hospitals for a three-year period. Subjects will be interviewed concerning their lifestyle (smoking and drug and alcohol use prior to conception and prenatally); reproductive histories (prior outcomes such as induced abortion and C-section); and other factors. Multivariate logistic regression will be used to analyze the effect these factors have on the occurrence and severity of placenta previa and abruptio placenta. Factors such as age, parity, and socioeconomic status will also be evaluated as potential risks and to determine their possible modifying effects for the reproductive and lifestyle exposures. The results of this study will demonstrate how exposures prior to conception may increase a woman's risk for placenta previa and how preconception and prenatal exposures may affect her risk for abruptio placenta.